Out of all DWG's I'm working with 80-90% contain these "xqc;" and similar character sequences, mostly at the beginning of text lines. And such text is always vertically misaligned. This is really annoying as I'm rarely creating new drawings myself from scratch, I'm doing my parts of the work started by other people who work in AutoCAD and GStarCAD.

Yes, but shouldn't they be eventually supported some day? And how about correction of vertical alignment? I know about DWG standard nightmare, but after all we need to work on these files and this is yet unavoidable.

Unfortunately, it's not realistic to implement all of Autocad's features in QCAD. Especially when it comes to text formatting, only the most commonly used subset of features is currently supported by QCAD. This will be extended, but it has never been the primary goal of QCAD to clone Autocad. DXF/DWG support should always be seen as a 'best effort' import.